Solar radiation's heat gain through windows often accounts for 50 percent of air-conditioning load in the summertime. If no existing shading exists in air-conditioned spaces such as offices, community rooms, or lobbies, window shading should be considered.

Types

• Exterior shading
  • Architectural elements
    • Roof overhangs
    • Vertical shading devices
  • Awnings
  • Shading screens
• Interior shades
  • Blinds
  • Curtains
  • Sun screens
• Tinted film

Considerations

• Exterior shading should be engineered for correct summer solar angles to ensure effective shading.
• Tinted film is fragile and should not be installed in areas where objects or people come into contact with windows.
• Sunshades on south- and west-facing windows can be effective at improving comfort and reducing the need for air conditioning.
• Window treatments do not reduce air leakage and infiltration

Performance/Economics

• Venetian blinds reflect 40 to 60 percent of the sun's radiant energy. Low-e windows reduce energy costs by approximately 30 to 50 percent.
• Window tinting can reduce solar energy gain 25 to 55 percent.
• Vertical blinds reflect approximately 23 percent of the sun's radiant energy.
• Roller shades, depending on their composition, reflect 15 to 80 percent of the sun's radiant energy. Overhangs are most effective at midday.